Here are the side curtain frames, showing variation in design & size.
Even the pieces that slot into doors are different.
It is surprising that they both have the same little clip device for securing the access flap, and both of those are in good condition!
The larger frame (with bent attaching point) will do just fine, so tomorrow I will build a jig to modify the smaller one. This jig will be kept to make further frames at some point in the future.
I am talking with the upholsterer, regarding a production of a further quantity of curtains for sale.